Power valve arrangement

ABSTRACT

A CARBURETOR HAVING A FUEL BOWL OR RESERVOIR WITH A MAIN FUEL-METERING SYSTEM, INCLUDING A METERING RESTRICTION THEREFOR, IS PROVIDED WITH A SECOND PASSAGE MEANS IN PARALLEL WITH THE METERING RESTRICTION, THE SECOND PASSAGE MEANS IS NORMALLY MAINTAINED CLOSED BY A WEIGHTED VALVE MEMBER RESPONSIVE TO THE VACUUM GENERATED AT THE VENTURI OF THE CARBURETOR INDUCTION PASSAGE, WHEN A VENTURI VACUUM OF SUFFICIENT MAGNITUDE IS REALIZED THE SECOND PASSAGE MEANS IS AT LEAST PARTIALLY OPENED PERMITTING ADDITIONAL QUANTITIES OF FUEL TO FLOW TO THE MAIN DISCHARGE NOZZLE THEREBY ENRICHING THE FUEL-AIR RATIO OF THE COMBUSTIBLE MIXTURE FLOWING INTO THE ENGINE INTAKE MANIFOLD.

United States Patent [72] Inventor Alvin S. Lucas 33700 Edmonton,Fnrmlngton, Mich. 48024 [21] Appl. No. 786,320 [22] Filed Dec. 23, 1968[45] Patented June 28, 1971 [54] POWER VALVE ARRANGEMENT 3 Claims, 5Drawing Figs.

[52] US. Cl. 261/67, 261/69 [51] InLCl. F02m 7/12 [50] Field 0! Search261/69, 69.1, 51, 67

[56] References Cited UNITED STATES PATENTS 2,447,264 8/1948 Beardsley,Jr. 26l/69(. l )X 3,081,984 3/1963 Wise 261/69)( Primary Examiner-Tim R.Miles Attorney-Walter Potoroka, Sr.

ABSTRACT: A carburetor having a fuel bowl or reservoir with a mainfuel-metering system, including a metering restriction therefor, isprovided with a second passage means in parallel with the meteringrestriction; the second passage means is normally maintained closed by aweighted valve member responsive to thevacuum generated at the venturiof the carburetor induction passage, when a venturi vacuum of suflicientmagnitude is realized the second passage means is at least partiallyopened permitting additional quantities of fuel to flow to the maindischarge nozzle thereby enriching the fuel-air ratio of the combustiblemixture flowing into the engine intake manifold.

PATENTEnJuuzslsn 3588.058

sum 1 or 2 PART T/IWOT/YE 5* 41 V/A S LUCAS INVIJN'R m.

BYLOM WA POWER VALVE ARRANGEMENT BACKGROUND OF THE INVENTION It has beenaccepted practice to provide, in carburetor structures, a power fuelenrichment system comprised of a power valve assembly carried by thecarburetor in a manner so as to be affected by engine intake manifoldvacuum. The manifold vacuum acting on a movable pressure-responsivemember, which is adapted for operative engagement with the valving meansof the power valve assembly, at idle or normal load conditions, as wellas during engine deceleration, is strong enough to overcome a springresistance so as to maintain the valving means closed. When higher powerdemands place a greater load on the engine and manifold vacuum dropsbelow a predetermined value, the said spring overcomes the reducedvacuum thereby opening the valving means. Consequently, fuel flowsthrough the open valve means and ultimately into the carburetorinduction passage thereby enriching the otherwise normal fuel-airmixture. As engine demands are reduced manifold vacuum again increases.The increased vacuum acts on the pressure-responsive member to finallyovercome the resistance of the said spring thereby closing the valvingmeans and shutting off the added supply of fuel which is no longerrequired.

However, heretofore such power valve systems have not been entirelysuccessful especially in situations where the internal combustion enginemight exhibit manifold vacuum characteristics peculiar unto itself. Suchcharacteristics might exist for any of a number of reasons such as, forexample, engine intake and exhaust valve timing as well as the nominalsize of the carburetor induction passage as compared to the pistondisplacement. Nevertheless, regardless of the causation, it has beenfound that some engines produce, under part throttle operation andrelatively high air flows, a leaningout" of the fuel-air mixture. Insuch situations, the prior art power valve assemblies were usuallyincapable of correcting the fuel deficiency in the fuel-air ratiobecause the opening and closing of the power valve assembly was solelydependent upon the magnitude of the generated manifold vacuum.

Accordingly, the invention herein disclosed and claimed directs itselfto the solution of such problems as set out above including others whichwill become apparent.

SUMMARY OF THE INVENTION According to the invention, a power valvearrangement comprises a housing portion containing a valving memberwhich is adapted to be unseated from a cooperating seat member inresponse to vacuum created at the carburetor induction passage venturi.

Accordingly, a general object of this invention is to provide a powervalve arrangement responsive to induction passage venturi vacuum forsupplying additional quantities of fuel to the induction passage inorder to enrich the fuel-air ratio of the motive fluid flowingtherethrough during periods of relatively high rate of airflow throughthe induction passage.

Another object of this invention is to provide a power valve arrangementwherein a first power valve assembly effective for supplying firstadditional quantities of fuel to the engine is actuated in response tovacuum generated at the venturi of the carburetor induction passage andwherein a second power valve assembly effective for supplying secondadditional quantities of fuel to the engine is actuated in response tovacuum generated in the engine intake manifold.

Other objects and advantages of the invention will become apparent whenreference is made to the following detailed description considered inconjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. I is a cross-sectional view of a carburetor, mounted on an engineintake manifold, equipped with a power valve assembly constructed inaccordance with the teachings of the invention;

FIG. 2 is a graph of a typical performance curve of the invention shownin FIG. 1 when the carburetor fuel-air ratio is plotted against theairflow through the carburetor;

FIG. 3 is a side elevational view, with portions thereof cut away and incross section of a carburetor embodying a second form of the invention;

FIG. 4 is an enlarged cross-sectional view of a fragmentary portion ofcertain details of FIG. 3; and

FIG. 5 is a graph of a typical performance curve of the invention shownin FIG. 3 when the carburetor fuel-air ratio is plotted against theairflow through the carburetor.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now in greater detail tothe drawings, FIG. 1 illustrates a carburetor 10 having a body 12 withan induction passage 14 formed therethrough communicating with thepassageway 16 of the intake manifold 18, of an associated internalcombustion engine, upon which the carburetor 10 is mounted. Theinduction passage 14 may be comprised of an air inlet 20, a main venturi22 and a mixture outlet 24 in communication with manifold passageway 16.The flow through the induction passage 14 may be controlled by athrottle valve 26 mounted on a throttle shaft 28 for pivotal rotationtherewith so as to be variably positioned as by manual operationthereof. Usually an air cleaner (not shown) is operatively connected tothe air inlet.

Fuel is supplied to the induction passage 14 from a reservoir 30 which,in the example shown, is a float chamber of a fuel bowl assembly 31having a float 32 therein which, as is well known in the art, actuatcs afuel valve controlling a fuel inlet leading from any suitable source ofsupply.

A generally upwardly extending well or passageway 34 communicates at itsupper end with a main nozzle conduit 36 which discharges at the throatof the venturi 22. A second venturi 38 may be provided to form adischarge member for the main nozzle 36. A fixed main meteringrestriction 40, secured in a wall of the fuel bowl assembly 31, servesto communicate fuel from reservoir 30 to main fuel system passageway 34.As is usual practice, a suitable idle fuel system may be provided so asto, as is well known in the art, communicate between reservoir 30 andinduction passage 14. Such an idle fuel system may include dischargeports (as fragmentarily shown at 42 and 44) situated adjacent the edgeof the throttle valve 26 when the throttle valve is in its nominallyclosed or curb idle condition.

An auxiliary or power valve assembly 46 is comprised of a housingportion 48, which maybe formed integrally within the structure generallydefining the fuel bowl assembly 31, forming a chamber 50 the lower endof which may be provided with a valve seat member 52 having an annularseat 54 at its upper end and a calibrated restricted passageway 56 atits generally lower end. A spherical or ball-type valve 58 is normallyheld in seated engagement against cooperating seat 54 by av suitableweight member 60 also moveably contained within chamber 50. The upperend of chamber 50 is closed as by a cap 62. As shown, chamber 50, in thevicinity-of ball valve 58 and seat 54 is placed in communication withmain well 34 as by an intermediate conduit portion 564.

As the vehicle is started into motion by the movement of the throttlevalve 26 (in the counterclockwise direction in F IG. 1) in the openingdirection to some intermediate position as at 26a, the rate of airflowincreases past both the throttle valve 26 and the venturi 22. Since thecross-sectional area of the throat of the venturi 22 is fixed, suchincreases in the rate of airflow can be accomplished only by the airundergoing an increase in the velocity of flow.

As is well known in the art, after the throttle valve 26'has opened somepredetermined amount and if the velocity of airflow past the venturi 22has reached some predetermined rate, the fuel originally suppliedthrough the idle fuel supply discharge ports 42 and 44 is substantiallyterminated and the main fuel-metering system, comprised of mainrestriction 40, main well or passageway 3d and main nozzle conduit 36,

becomes the principal source of fuel with such fuel being dischargedthrough the auxiliary or booster venturi 38 into the induction passage14.

As illustrated generally by the graph of FIG. 2, when the throttle valve26 is moved from its nominally closed or curb idle condition to a morenearly opened condition the fuel-air ratio (F/A) begins to lean out inaccordance with the curve identified as part throttle" and extendingfrom point A to point B. As can be seen, this is accompanied by anincrease in the rate of airflow passing through the induction passage.If such leaning out of the fuel-air ratio were to continue the ratio offuelto air might become so low as to be insufficient to provide asuitable combustible mixture to the engine during periods of engineoperation as where demands for highe. power place a greater load on theengine requiring, in turn, high airflows. 1

It should, of course, be remembered that during the full range ofoperation of the main fuel system the rate of fuel flow through the mainnozzle conduit 36 is determined by the pressure differential across mainmetering restriction 40 and the efi'ective cross-sectional area of thecalibrated passageway 41 formed therethrough. 7

However, in FIG. 1, the first embodiment of the invention. when the airflow through induction passage 14 reaches a predetermined value asrepresented by point B the vacuum generated by the air flowing pastventuri 22 becomes sufficient to start to lift valve member 58 off itscooperating seat 54 against the resistance of weight 60. As this happensan additional quantity of fuel is caused to flow from reservoir 30through calibrated passageway 56 into chamber 50 and through conduit 64from where it flows into well 34 and through main nozzle conduit 36discharging into the induction passage 14. Such fuel flowing throughcalibrated passageway or restriction 56 is in addition to that rate offuel flow normally metered by main restriction 40. Further, the rate ofsuch additional fuel flow will increase as the throttle valve 26 isfurther moved to a more nearly wide open position because such furtheropening movements of the throttle valve cause increases in the velocityof airflow past venturi 22 which, in turn, causes a greater pressuredifferential across the secondary metering restriction 56.

Accordingly, it can be seen, in FIG, 2, that as the throttle valve 26 isprogressively opened from point B to a wide open throttle (WOT)condition of point C (with airflow through the induction passage 14increasing) that an enriched fuel-air ratio as defined by the line fromB to C is achieved. The portion of the graph represented by line c-D isachieved by maintaining the throttle at WOT and increasing the engineload so as to progressively reduce the airflow.

As can be seen from the preceding, the invention thus far disclosed anddescribed provides a valving arrangement which is actuated in responseto the rate of air flow through the carburetor induction passage forproviding additional quantities of fuel in order to thereby enrich thefuel-air ratio of the mixture being supplied to the engine duringperiods of increased engine load. 1

Point 13, used to designate that particular point representative of thevalve of airflow at which valve 58 will start to open, can, of course,be shifted to either the left or right in FIG. 2 by changing any of anumber of actors. For example, placing a calibrated atmospheric bleedbetween chamber 50 and the ambient atmosphere would have the effect ofreducing the value of the vacuum communicated to chamber 50 therebycausing point B to beeffectively moved to the right in FIG. 2 so as torequire a higher airflow before valve 58 starts to open.

Point B could be effectively moved to the left by reducing the weight ofvalve member 58 or that of member 60. The general slope or shape ofcurve B-C can also be modified by changing the size of the calibratedpassageway or secondary restriction 56. Further, greater tailoring ofthe additional fuel can be achieved by employing a contoured valve inplace of ball valve 58. Such changes and modifications are, of course,specifically contemplated and accordingly within the scope of theinvention.

SECOND EMBODIMENT OF THE INVENTION Another embodiment of the inventionis disclosed by F105. 3 and 4 wherein FIG. 3 illustrates a carburetorcomprising a body 112 with a throttle body 114 and air intake 116,secured thereto at opposite ends thereof, with an induction passage 118formed therethrough adapted to be controlled at one end by a choke valve120 secured for rotation with a choke shaft 122 suitably journaled inthe walls 124 and 126 of air intake 116. The choke valve 120 and shaft122 may be positioned as by an automatic choke mechanism many types ofwhich are well known in the art.

Throttle body 114, suitably secured to an induction or intake manifold128 of an internal combustion engine, continues to define the inductionpassage 118 and places the induction passage 118 in communication withthe intake passage 130 of the engine intake manifold 128. A throttleshaft 132, joumaled in the walls of throttle body 114, has securedthereto, for rotation therewith, a throttle valve 134 which isillustrated in a partly open or part throttle position therebypermitting a controlled flow of combustible mixtures to flow through theinduction passage 118, past throttle valve 134 and into passage 130 ofintake manifold 128. Throttle shaft 132 may, of course, be connected tosuitable throttle actuating mechanism, as is well known in the art, asfor manual actuation thereof.

A main fuel nozzle 136 having its discharge end 138 situated generallywithin the throat of a main venturi 140, formed in the induction passage118, communicates at its other end with a passage 142 which, in turn, isin communication with passageway or conduit 144 and a main well 146.Conduit 144 and main well 146 may be formed in the metering section ofan associated fuel supply or fuel bowl assembly 148 suitably secured tothe carburetor body 112.

The fuel bowl assembly 148, provided with a suitable fuel inlet, definesa fuel reservoir or chamber 150 for containing therein a quantity ofliquid fuel the level of which may be determined as by any suitablemeans such as a float 151 and a float-controlled fuel inlet valvearrangement many of which are well known in the art.

A main fuel restriction 152, threadably received through a wall 154 infuel bowl assembly 148, has a calibrated restriction or passageway 156formed therethrough for communication between chamber 150 and main well146. A power valve assembly 158, also threadably received through wall154, is adapted to at times complete communication between chamber 150and well 146 so as to thereby complete a second passage means betweenfuel chamber 150 and well 146 paralleling restricted passageway 156. I

A cavity 166, formed in carburetor body 112 generally, surrounds one endof power valve assembly 158 and is in communication with conduit 168.Conduit 168, provided with a suitable restriction 172 therein,communicates with a conduit 174 formed in intake manifold 128 andcommunicating with intake passageway 130.

FIG. 4 illustrates, in enlarged cross-sectional view, the power valveassembly 158 as being comprised of a housing 184 which cooperates with acoverlike member 186 to peripherally secure a pressure-responsivediaphragm member 188 therebetween. A sealing gasket 1% may be providedin order to prevent damage to the periphery of diaphragm 188. The areagenerally between diaphragm 188 and cover member 186 is vented to thepressure within chamber 166 as by an opening or aperture 191 formed incover 186.

A stem member 192 secured at one end thereof to diaphragm 188, as byoppositely disposed plates 194 and 196 and a peened-over portion 198,carries a valve portion 200 thereon which is adapted to at times seatagainst a valve seat 202 formed in the end of housing or body 184. Atother times, a spring 204 engaging, an abutment 205 carried by stem 192,moves stem 192 and valve member 200 away from seat 202 so as to completecommunication between fuel bowl chamber 150 and the interior chamber 206of valve housing 184. A plurality of generally axially extending flutesor guides 2118 may be formed within chamber 206 so as to generally guidethe movement of stem 192 without in any material way restricting flowfrom the inlet, defined by opened valve 200 and seat 202, to theradially directed passageways or conduits 210 and 212 formed in powervalve housing 184. Conduits 210 and 212, in turn, communicate with anannular chamber 214, formed in wall 154, which communicates with mainwell 146 as by an intermediate conduit 216 and a restriction 215 havinga calibrated passageway 217 formed therethrough.

As illustrated in FIG. 3, an auxiliary power valve assembly 220,provided generally within the fuel bowl assembly 148, is comprised of achamber 222 having its upper end capped as by member 224 and a valveseat 226 provided near its lower end. A ball valve 228 is urged intooperative engagement with seat 226 as by means of a cooperating weightmember 230 loosely contained within chamber 222. A metering restriction232, having a calibrated passageway 234 formed therethrough, is receivedwithin the lower end of chamber 222. An intermediate conduit orpassageway 236 serves to communicate between chamber 222 and main well146.

Generally, it is well known in the art that the value of manifold vacuumgenerated by the engine will vary depending on such factors as enginespeed, road load and throttle valve position. For example, with theengine operating at idle, a relatively high value of manifold vacuumwill be generated because, at such time, the throttle valve 134 is inits nominally closed position illustrated in phantom line at 134a.During such time, as is well known in the art, the principal means forsupplying fuel to the induction passage 118 and intake manifold 123 isby suitable conduitry and metering means collectively referred to as theidle fuel system. Such idle fuel systems are well known in the art and,for purposes of clarity, are not illustrated herein since the practiceof the invention is not in any way limited to or by an associated idlefuel system. During such idle engine operation the manifold vacuum maybe of a value in the order of 16.0 to 19.0 inches of mercury g)- As thevehicle is started into motion by the movement of the throttle valve 134(in the clockwise direction in FIG. 3) in the opening direction, theload placed on the engine increases and because of the throttle valve134 being moved toward a more fully opened position the value of themanifold vacuum decreases. The amount of decrease will depend on theload placed on the engine as well as the rapidity with which thethrottle valve 134 is rotated from its nominally closed position towarda more fully opened position. If the engine load is sufficiently greatand the opening movement of the throttle is sufficiently rapid, themanifold vacuum may, during this time, decrease to a value in the orderof 1.0 to 4.0 inches Hg.

Further, when the vehicle is decelerating with the throttle valvenominally closed and the vehicle driving the engine, the valve of thegenerated manifold vacuum may well substantially exceed that establishedat idle engine operation and be in the order of2 l .0 to 22.0 inches Hg.

Accordingly, it can be seen that manifold or enginegenerated vacuum isrelated to engine operation and as such may be employed as not only anactuating force but also as a control parameter for related devices.Further, it can be seen that chamber 166 and one side 218 of diaphragm188 will be exposed to manifold vacuum of a varying value, dependingupon throttle position and engine load, by virtue of the communicationestablished by serially situated conduits 168 and 174.

The main fuel system, comprising restriction 152, main well 146,conduits 144, 142 and main nozzle 136 serves to supply fuel to theinduction passage 118 generally during normal offidle engine operation,as is well known in the art. Further, the manifold vacuum acting ondiaphragm 188 at conditions of idle, normal load' conditions ordeceleration is sufficient to overcome the force of spring 204 therebyholding valve member 200 shut against valve seat 202. However, whendemands for higher power place a greater load on the engine and manifoldvacuum decreases below a predetermined value,

spring 204 overcomes the pressure differential across diaphragm 188 andmoves valve 200 off seat 222 thereby permitting additional fuel to flowfrom chamber 150 through the power valve inlet, interior chamber 206 andout through radial passages 210, 212 and through annulus 214 andpassageway 216, including restriction 215, into main well 146. The rateof fuel flow from the fuel bowl chamber 150 to main well 146 beingthusly increased by the opening of the power valve assembly 158 causesan enrichment ofthe flow through the main fuel discharge nozzle 136resulting in, of course, the ultimate enrichment of the fuel-air mixturebeing supplied to the induction passage 118 and intake manifoldpassageway 130. As engine power demands are reduced, manifold vacuumincreases; when the vacuum has sufficiently increased, the pressuredifferential created across diaphragm 188 overcomes the force of spring204 and again closes valve 200 against valve seat 202.

For purposes of illustration, let it be assumed that a particularengine, on which the structure of FIG. 3 is situated, has an operatingcharacteristic which causes the fuel-air ratio curve to be asillustrated in FIG. 5 and defined therein by points A, B and X. Incomparing the graphs of FIGS. and 5, it can be seen that the portionbetween points A and B corresponds to that portion between points A andB. However, because of certain engine characteristics the fuel-air ratioat higher airflows than that of point B tends to become overly lean forengine requirements. Such characteristics have not been successfullyovercome by the employment of only a manifold vacuum-responsive powervalve assembly.

Accordingly, the auxiliary power valve assembly 220 serves to overcomesuch engine-operating characteristics by providin g an additional rateof fuel flow, in parallel to that rate determined by main meteringrestriction 152, so as to enrich the fuel-air ratio to the degree thatthe actual fuel-air ratio is in accordance with that portion of thecurve between points B and X. The opening and closing of valve 228 is,of course, in accordance with the mode of operation of the power valveassembly 46 of FIG. 1.

In the arrangement of FIG. 3, when power valve assembly 158 would becomeopened, so as to supply additional enrichening fuel, the power valveassembly 220 would continue to supply its contribution of enricheningfuel assuming, of course, that sufficient airflows and venturi vacuum atventuri 140 existed. This period wherein such additional fuel issupplied by power valve assembly 158 is illustrated generally by thatportion of the curve between points X and C of FIG, 5.

Although only two selected embodiments of the invention have beendisclosed and described, it is apparent that other embodiments andmodifications of the invention are possible within the scope of theappended claims.

Iclaim:

1. A carburetor for an internal combustion engine, comprising aninduction passage, a venturi formed in said induction passage, a fuelreservoir, a main fuel-metering system including first main meteringrestriction means, said main fuel-metering system communicating betweensaid reservoir and said induction passage in the vicinity of saidventuri, and a power valve arrangement for at times supplying anadditional rate of fuel flow to said main metering system in order tothereby enrichen the fuel-air ratio of the combustible mixture beingsupplied to said engine, said power valve arrangement comprising aninlet communicating with said reservoir, an outlet communicating withsaid main metering system and pressure-responsive valve means situatedbetween said inlet and said outlet for at times completing communicationtherebetween, said pressure-responsive valve means being exposed to andresponsive to vacuum created at said venturi and being effective tocomplete said communication between said inlet and said outlet wheneverthe value of said venturi vacuum is at least equal to a predeterminedvacuum value, a second pressure-respom sive valving means situation inparallel to said first metering restriction means and saidfirst-mentioned pressure-responsive valve means, said secondpressure-responsive valving means including a second inlet communicatingwith said reservoir and a second outlet communicating with said mainmetering system, said second pressure-responsive valving means beingexposed to and responsive to the vacuum created in the intake manifoldof said engine, and said second pressureresponsive means being effectivewhenever the value of said manifold vacuum is less than a predeterminedvalue of vacuum to complete communication between said second inlet andsaid second outlet, said first power valve arrangement and said secondpressure-responsive valving means being constructed and arranged so thatthey operate intermittently to supplement fuel supply by said mainfuel-metering system and so that said power valve arrangement responsiveto venturi vacuum opens before said second pressure-responsive valvingmeans and upon continued acceleration both said power valve arrangementand said second pressure-valving means supply additional fuel to saidmain fuel-metering system.

2. A carburetor for an internal combustion engine accord ing to claim 1wherein said power valve arrangement includes second meteringrestriction means situated generally in said first-mentionecl inlet andserially between said reservoir and said first-mentionedpressure-responsive valve means, and third metering restriction meanssituated in said second outlet of said second pressure-responsivevalving means.

3. A carburetor for an internal combustion engine according to claim 1including resilient biasing means for continually urging said secondpressure-responsive valving means toward an open condition so as tocomplete communication between said second inlet and said second outlet.

